Former Sen. Rick Santorum’s (Pa.) support for a troubled Clinton administration judicial nominee is drawing fresh scrutiny from conservatives as the GOP presidential candidate struggles to regain his footing against presumptive nominee Mitt Romney.

Some Republicans see Santorum’s 1998 backing of Frederica Massiah-Jackson to be a district court judge in Philadelphia as conflicting with the staunch conservative persona he has put forward.

President Bill Clinton withdrew Massiah-Jackson’s nomination March 16, 1998, one day before the Senate was going to vote — and likely not confirm her. She had been accused of being biased against police and prosecutors by the Pennsylvania District Attorneys Association, including the Philadelphia district attorney, the Philadelphia Fraternal Order of Police, Lodge No. 5 and the National Association of Police Officers.

A former Judiciary Committee GOP staffer believes the incident shows that Santorum is not the conservative stalwart he claims to be and that he was too deferential to centrist Sen. Arlen Specter, Pennsylvania’s senior Republican Senator at the time.

“While Santorum holds himself out during this campaign to be a tried and true conservative, his Senate record says differently,” the committee staffer said. “His support of labor and earmarks came out during the debates, and the Massiah-Jackson issue is another instance of that, and a egregious one. He practically outsourced all Pennsylvania judges to Arlen Specter.”

A spokesman for the Santorum campaign did not return a phone call seeking comment.

Critics of Santorum argue that his support of earmarks for his state — which conservatives began to oppose in recent years because they often fund what they argue are wasteful pet projects — call into question his conservative bona fides.

There has also been criticism of Santorum’s backing of the Davis-Bacon Act, a Depression-era law that requires workers be paid prevailing wages on federally funded projects. Republicans typically oppose Davis-Bacon because they argue it raises the cost of projects.

In a debate in February, Santorum defended earmarks, arguing that some are good and some are bad and that there was abuse of the process. With regard to Davis-Bacon, in a speech to the Detroit Economic Club in February, Santorum said, “I’ve been attacked as the ‘big union’ Republican ... But I went back to look at my AFL-CIO scorecard, and I had a 13 percent rating. If that’s ‘big union’ in the Republican Party, I guess we’ve narrowed the field quite a bit, haven’t we?”

A GOP strategist said that the Massiah-Jackson incident only further highlights the “weakness in his narrative.”

“Santorum claims to have a staunch, solid conservative record, but the debates revealed his support for earmarks and being an insider, part of the ‘Washington Club,’ and this is further evidence of that,” the strategist continued.

“He will make exceptions,” the strategist said, which leads to inconsistencies in his positions — something that gives some conservatives pause.

“He does have the evangelicals solidly on his side, but not the rest of the conservative vote,” the strategist added.

Their comments come as the Republican Party establishment is increasingly pushing to close ranks behind Romney, who leads in the delegate race and bagged primary victories earlier this week in Wisconsin, Maryland and the District of Columbia. Santorum hopes to mount a comeback by winning his home state’s April 24 primary.

“His days as a Republican nominee contender are clearly numbered, with Romney as the frontrunner that Republicans are coalescing around,” said Ron Bonjean, a former GOP leadership staffer now at Singer Bonjean Strategies.

His comments echo those of 2008 GOP presidential nominee Sen. John McCain (Ariz.), who said earlier this week that it is “irrelevant” whether Santorum stays in.

But Santorum said earlier this week after the primary results had come in that he intends to stay in the race. He met with conservative leaders outside Washington, D.C., on Thursday to craft a plan to help defeat Romney.

However, not all Republicans agree that the Massiah-Jackson issue shows Santorum as a wavering conservative.

“My recollection is that Sen. Santorum took the position that Judge Massiah-Jackson was entitled to a hearing and a vote,” a former GOP Judiciary staffer said. “He returned the blue slip. But was he a supporter or an advocate for her? Not that I recall. He could have introduced her at the hearing, but that was just good protocol.”

“As you can expect, since she was from Philadelphia, Sen. Specter was the one actively pushing for her, not Sen. Santorum,” the staffer said. “With opposition from Pennsylvania law enforcement groups and prosecutors, it became clear she was going to be defeated. Sen. Santorum and Sen. Specter both had urged her to withdraw and Sen. Santorum was, I believe, going to vote against her.”

Clinton nominated Massiah-Jackson in July 1997 for a seat on the U.S. District Court for the Eastern District of Pennsylvania. She received two hearings in the Senate Judiciary Committee, something that does not typically happen without the backing of both home-state Senators.

The first hearing was held in October 1997, and the panel ultimately approved her by voice vote. She subsequently received a second hearing in March 1998 after law enforcement and prosecutors came out against her nomination and she became the target of conservative groups. The second hearing came at the urging of several Senators including Santorum, according to a Senate Republican Policy Committee policy paper from the 105th Congress.

At the second hearing, she appeared before the panel and answered questions for several hours where she said that her record had been “wildly distorted” and that the charges were untrue, the Policy Committee paper said. She ultimately requested that her nomination be withdrawn, which the White House did the day before the Senate vote.